Controlling wave fronts with tunable disordered non-Hermitian multilayers

Abstract

Unique and flexible properties of non-Hermitian photonic systems attract ever-increasing attention via delivering a whole bunch of novel optical effects and allowing for efficient tuning light-matter interactions on nano- and microscales. Together with an increasing demand for the fast and spatially compact methods of light governing, this peculiar approach paves a broad avenue to novel optical applications. Here, unifying the approaches of disordered metamaterials and non-Hermitian photonics, we propose a conceptually new and simple architecture driven by disordered loss-gain multilayers and, therefore, providing a powerful tool to control both the passage time and the wave-front shape of incident light with different switching times. For the first time we show the possibility to switch on and off kink formation by changing the level of disorder in the case of adiabatically raising wave fronts. At the same time, we deliver flexible tuning of the output intensity by using the nonlinear effect of loss and gain saturation. Since the disorder strength in our system can be conveniently controlled with the power of the external pump, our approach can be considered as a basis for different active photonic devices.

Cascade of the delocalization transition in a non-Hermitian interpolating Aubry-Andr{é}-Fibonacci chain

“…Moreover, we have found that the real-complex transition also demonstrates cascade behavior, similar to the delocalization transition for the excited states. Besides the non-reciprocal hopping, the non-Hermiticity can also be induced by the on-site gain/loss [28,36,[71][72][73]. It should be interesting to study the delocalization transition and the critical behavior in the IAAF model with on-site gain/loss.…”

Tunable virtual gain in resonantly absorbing media

“…On the other hand, the incoherent waveforms with longer characteristic timescales such as incoherent solitons [57] and optical kinks [58,59] can also withstand absorption in resonant media. We also mention the studies of ultrashort pulses [60] and wavefront propagation [61] in disordered resonantly absorbing and amplifying media. The role of driving-field decay rate in superradiance and subradiance dynamics was revealed recently [62].…”

CPA-Lasing Associated with the Quasibound States in the Continuum in Asymmetric Non-Hermitian Structures

“…The most popular transverse geometry is a multilayer structure with alternating loss and gain media. Being a non-Hermitian generalization of the photonic crystal concept, such a multilayer attracts much attention due to its simplicity for analysis and availability for unusual optical responses, such as anisotropic transmission resonances, resonant scattering, nonlinear saturation effects, − nonlocality, pulse-propagation effects, , effects of disorder, and so forth. From the more general perspective, many of these effects can be treated as “anomalies” in light scattering , being described by means of scattering matrix technique. , The features of light scattering on dielectric structures were deeply studied in recent years. − …”